OCTOBER TERM, 1993
Syllabus
STAPLES v. UNITED STATES
CERTIORARI TO THE UNITED STATES COURT OF APPEALS FOR THE TENTH
CIRCUIT
No.92-1441. Argued November 30, 1993-Decided May 23,1994
The National Firearms Act criminalizes possession of an
unregistered "firearm," 26 U. S. C. § 5861(d), including a
"machinegun," § 5845(a)(6), which is defined as a weapon that
automatically fires more than one shot with a single pull of the
trigger, § 5845(b). Petitioner Staples was charged with possessing
an unregistered machine gun in violation of § 5861(d) after
officers searching his home seized a semiautomatic riflei. e., a
weapon that normally fires only one shot with each trigger pullthat
had apparently been modified for fully automatic fire. At trial,
Staples testified that the rifle had never fired automatically
while he possessed it and that he had been ignorant of any
automatic firing capability. He was convicted after the District
Court rejected his proposed jury instruction under which, to
establish a § 5861 (d) violation, the Government would have been
required to prove beyond a reasonable doubt that Staples knew that
the gun would fire fully automatically. The Court of Appeals
affirmed, concluding that the Government need not prove a
defendant's knowledge of a weapon's physical properties to obtain a
conviction under § 5861(d).
Held: To obtain a § 5861(d) conviction, the Government should
have been required to prove beyond a reasonable doubt that Staples
knew that his rifle had the characteristics that brought it within
the statutory definition of a machinegun. Pp. 604-619.
(a) The common-law rule requiring mens rea as an element of a
crime informs interpretation of § 5861(d) in this case. Because
some indication of congressional intent, express or implied, is
required to dispense with mens rea, § 5861(d)'s silence on the
element of knowledge required for a conviction does not suggest
that Congress intended to dispense with a conventional mens rea
requirement, which would require that the defendant know the facts
making his conduct illegal. Pp. 604-606.
(b) The Court rejects the Government's argument that the Act
fits within the Court's line of precedent concerning "public
welfare" or "regulatory" offenses and thus that the presumption
favoring mens rea does not apply in this case. In cases concerning
public welfare offenses, the Court has inferred from silence a
congressional intent to dispense with conventional mens rea
requirements in statutes that regulate potentially harmful or
injurious items. In such cases, the Court has reasoned
601
that as long as a defendant knows that he is dealing with a
dangerous device of a character that places him in responsible
relation to a public danger, he should be alerted to the
probability of strict regulation, and is placed on notice that he
must determine at his peril whether his conduct comes within the
statute's inhibition. See, e. g., United States v. Balint,
258 U. S. 250; United
States v. Freed,
401
U. S. 601. Guns, however, do not fall within the category of
dangerous devices as it has been developed in public welfare
offense cases. In contrast to the selling of dangerous drugs at
issue in Balint or the possession of hand grenades considered in
Freed, private ownership of guns in this country has enjoyed a long
tradition of being entirely lawful conduct. Thus, the destructive
potential of guns in general cannot be said to put gun owners
sufficiently on notice of the likelihood of regulation to justify
interpreting § 5861 (d) as dispensing with proof of knowledge of
the characteristics that make a weapon a "firearm" under the
statute. The Government's interpretation potentially would impose
criminal sanctions on a class of persons whose mental
state-ignorance of the characteristics of weapons in their
possession-makes their actions entirely innocent. Had Congress
intended to make outlaws of such citizens, it would have spoken
more clearly to that effect. Pp. 606-616.
(c) The potentially harsh penalty attached to violation of §
5861 (d)up to 10 years' imprisonment-confirms the foregoing reading
of the Act. Where, as here, dispensing with mens rea would require
the defendant to have knowledge only of traditionally lawful
conduct, a severe penalty is a further factor tending to suggest
that Congress did not intend to eliminate a mens rea requirement.
Pp. 616-619.
(d) The holding here is a narrow one that depends on a
commonsense evaluation of the nature of the particular device
Congress has subjected to regulation, the expectations that
individuals may legitimately have in dealing with that device, and
the penalty attached to a violation. It does not set forth
comprehensive criteria for distinguishing between crimes that
require a mental element and crimes that do not. Pp. 619-620.
971 F.2d
608, reversed and remanded.
THOMAS, J., delivered the opinion of the Court, in which
REHNQUIST, C. J., and SCALIA, KENNEDY, and SOUTER, JJ., joined.
GINSBURG, J., filed an opinion concurring in the judgment, in which
O'CONNOR, J., joined, post, p. 620. STEVENS, J., filed a dissenting
opinion, in which BLACKMUN, J., joined, post, p. 624.
Jennifer L. De Angelis argued the cause for petitioner.
With her on the brief was Clark O. Brewster.
602
James A. Feldman argued the cause for the United States.
With him on the brief were Solicitor General Days, Acting
Assistant Attorney General Keeney, Deputy Solicitor General Bryson,
and John F. De Pue.
JUSTICE THOMAS delivered the opinion of the Court.
The National Firearms Act makes it unlawful for any person to
possess a machine gun that is not properly registered with the
Federal Government. Petitioner contends that, to convict him under
the Act, the Government should have been required to prove beyond a
reasonable doubt that he knew the weapon he possessed had the
characteristics that brought it within the statutory definition of
a machinegun. We agree and accordingly reverse the judgment of the
Court of Appeals.
I
The National Firearms Act (Act), 26 U. S. C. §§5801-5872,
imposes strict registration requirements on statutorily defined
"firearms." The Act includes within the term "firearm" a
machinegun, § 5845(a)(6), and further defines a machinegun as "any
weapon which shoots, ... or can be readily restored to shoot,
automatically more than one shot, without manual reloading, by a
single function of the trigger," § 5845(b). Thus, any fully
automatic weapon is a "firearm" within the meaning of the AcU Under
the Act, all firearms must be registered in the National Firearms
Registration and Transfer Record maintained by the Secretary of the
Treasury. § 5841. Section 5861(d) makes it a crime, punish-
1 As used here, the terms "automatic" and "fully automatic"
refer to a weapon that fires repeatedly with a single pull of the
trigger. That is, once its trigger is depressed, the weapon will
automatically continue to fire until its trigger is released or the
ammunition is exhausted. Such weapons are "machine guns" within the
meaning of the Act. We use the term "semiautomatic" to designate a
weapon that fires only one shot with each pull of the trigger, and
which requires no manual manipulation by the operator to place
another round in the chamber after each round is fired.
603
able by up to 10 years in prison, see § 5871, for any person to
possess a firearm that is not properly registered.
Upon executing a search warrant at petitioner's home, local
police and agents of the Bureau of Alcohol, Tobacco and Firearms
(BATF) recovered, among other things, an AR-15 rifle. The AR-15 is
the civilian version of the military's M-16 rifle, and is, unless
modified, a semiautomatic weapon. The M-16, in contrast, is a
selective fire rifle that allows the operator, by rotating a
selector switch, to choose semiautomatic or automatic fire. Many
M-16 parts are interchangeable with those in the AR-15 and can be
used to convert the AR-15 into an automatic weapon. No doubt to
inhibit such conversions, the AR-15 is manufactured with a metal
stop on its receiver that will prevent an M-16 selector switch, if
installed, from rotating to the fully automatic position. The metal
stop on petitioner's rifle, however, had been filed away, and the
rifle had been assembled with an M-16 selector switch and several
other M-16 internal parts, including a hammer, disconnector, and
trigger. Suspecting that the AR-15 had been modified to be capable
of fully automatic fire, BATF agents seized the weapon. Petitioner
subsequently was indicted for unlawful possession of an
unregistered machinegun in violation of § 5861(d).
At trial, BATF agents testified that when the AR-15 was tested,
it fired more than one shot with a single pull of the trigger. It
was undisputed that the weapon was not registered as required by §
5861(d). Petitioner testified that the rifle had never fired
automatically when it was in his possession. He insisted that the
AR-15 had operated only semiautomatically, and even then
imperfectly, often requiring manual ejection of the spent casing
and chambering of the next round. According to petitioner, his
alleged ignorance of any automatic firing capability should have
shielded him from criminal liability for his failure to register
the weapon. He requested the District Court to instruct the jury
that, to establish a violation of § 5861(d), the Government must
prove
604
beyond a reasonable doubt that the defendant "knew that the gun
would fire fully automatically." 1 App. to Brief for Appellant in
No. 91-5033 (CAlO), p. 42.
The District Court rejected petitioner's proposed instruc-
tion and instead charged the jury as follows:
"The Government need not prove the defendant knows he's dealing
with a weapon possessing every last characteristic [which subjects
itp to the regulation. It would be enough to prove he knows that he
is dealing with a dangerous device of a type as would alert one to
the likelihood of regulation." Tr. 465.
Petitioner was convicted and sentenced to five years' probation
and a $5,000 fine.
The Court of Appeals affirmed. Relying on its decision in United
States v. Mittleider,
835 F.2d
769 (CAlO 1987), cert. denied, 485 U. S. 980 (1988), the court
concluded that the Government need not prove a defendant's
knowledge of a weapon's physical properties to obtain a conviction
under § 5861(d).
971 F.2d
608, 612-613 (CAlO 1992). We granted certiorari, 508 U. S. 939
(1993), to resolve a conflict in the Courts of Appeals concerning
the mens rea required under § 5861(d).
II A
Whether or not § 5861(d) requires proof that a defendant knew of
the characteristics of his weapon that made it a "firearm" under
the Act is a question of statutory construction. As we observed in
Liparota v. United States,
471 U. S. 419 (1985),
"[t]he definition of the elements of a criminal offense is
entrusted to the legislature, particularly in the case of federal
crimes, which are solely creatures of statute." Id., at 424 (citing
United States v. Hudson, 7 Cranch 32
2 In what the parties regard as a mistranscription, the
transcript contains the word "suggested" instead of "which subjects
it."
605
(1812)). Thus, we have long recognized that determining the
mental state required for commission of a federal crime requires
"construction of the statute and ... inference of the intent of
Congress." United States v. Balint,
258 U. S. 250, 253
(1922). See also Liparota, supra, at 423.
The language of the statute, the starting place in our inquiry,
see Connecticut Nat. Bank v. Germain,
503 U. S. 249, 253-254
(1992), provides little explicit guidance in this case. Section
5861(d) is silent concerning the mens rea required for a violation.
It states simply that "[i]t shall be unlawful for any person ... to
receive or possess a firearm which is not registered to him in the
National Firearms Registration and Transfer Record." 26 U. S. C. §
5861(d). Nevertheless, silence on this point by itself does not
necessarily suggest that Congress intended to dispense with a
conventional mens rea element, which would require that the
defendant know the facts that make his conduct illegal. See Balint,
supra, at 251 (stating that traditionally, "scienter" was a
necessary element in every crime). See also n. 3, infra. On the
contrary, we must construe the statute in light of the background
rules of the common law, see United States v. United States Gypsum
Co.,
438 U. S.
422, 436-437 (1978), in which the requirement of some mens rea
for a crime is firmly embedded. As we have observed, "[t]he
existence of a mens rea is the rule of, rather than the exception
to, the principles of Anglo-American criminal jurisprudence." Id.,
at 436 (internal quotation marks omitted). See also Morissette v.
United States,
342 U.
S. 246, 250 (1952) ("The contention that an injury can amount
to a crime only when inflicted by intention is no provincial or
transient notion. It is as universal and persistent in mature
systems of law as belief in freedom of the human will and a
consequent ability and duty of the normal individual to choose
between good and evil").
There can be no doubt that this established concept has
influenced our interpretation of criminal statutes. Indeed, we have
noted that the common-law rule requiring mens rea
606
has been "followed in regard to statutory crimes even where the
statutory definition did not in terms include it." Balint, supra,
at 251-252. Relying on the strength of the traditional rule, we
have stated that offenses that require no mens rea generally are
disfavored, Liparota, supra, at 426, and have suggested that some
indication of congressional intent, express or implied, is required
to dispense with mens rea as an element of a crime. Cf. United
States Gypsum, supra, at 438; Morissette, supra, at 263.
According to the Government, however, the nature and purpose of
the Act suggest that the presumption favoring mens rea does not
apply to this case. The Government argues that Congress intended
the Act to regulate and restrict the circulation of dangerous
weapons. Consequently, in the Government's view, this case fits in
a line of precedent concerning what we have termed "public welfare"
or "regulatory" offenses, in which we have understood Congress to
impose a form of strict criminal liability through statutes that do
not require the defendant to know the facts that make his conduct
illegal. In construing such statutes, we have inferred from silence
that Congress did not intend to require proof of mens rea to
establish an offense.
For example, in Balint, we concluded that the Narcotic Act of
1914, which was intended in part to minimize the spread of
addictive drugs by criminalizing undocumented sales of certain
narcotics, required proof only that the defendant knew that he was
selling drugs, not that he knew the specific items he had sold were
"narcotics" within the ambit of the statute. See Balint, supra, at
254. Cf. United States v. Dotterweich,
320 U. S. 277, 281 (1943)
(stating in dicta that a statute criminalizing the shipment of
adulterated or misbranded drugs did not require knowledge that the
items were misbranded or adulterated). As we explained in
Dotterweich, Balint dealt with "a now familiar type of legislation
whereby penalties serve as effective means of regulation. Such
legislation dispenses with the conven-
607
tional requirement for criminal conduct-awareness of some
wrongdoing." 320 U. S., at 280-281. See also Morissette, supra, at
252-256.
Such public welfare offenses have been created by Congress, and
recognized by this Court, in "limited circumstances." United States
Gypsum, supra, at 437. Typically, our cases recognizing such
offenses involve statutes that regulate potentially harmful or
injurious items. Cf. United States v. International Minerals &
Chemical Corp.,
402
U. S. 558, 564-565 (1971) (characterizing Balint and similar
cases as involving statutes regulating "dangerous or deleterious
devices or products or obnoxious waste materials"). In such
situations, we have reasoned that as long as a defendant knows that
he is dealing with a dangerous device of a character that places
him "in responsible relation to a public danger," Dotterweich,
supra, at 281, he should be alerted to the probability of strict
regulation, and we have assumed that in such cases Congress
intended to place the burden on the defendant to "ascertain at his
peril whether [his conduct] comes within the inhibition of the
statute." Balint, supra, at 254. Thus, we essentially have relied
on the nature of the statute and the particular character of the
items regulated to determine whether congressional silence
concerning the mental element of the offense should be interpreted
as dispensing with conventional mens rea requirements. See
generally Morissette, supra, at 252-260.3
3 By interpreting such public welfare offenses to require at
least that the defendant know that he is dealing with some
dangerous or deleterious substance, we have avoided construing
criminal statutes to impose a rigorous form of strict liability.
See, e. g., United States v. International Minerals & Chemical
Corp.,
402 U. S.
558, 563-564 (1971) (suggesting that if a person shipping acid
mistakenly thought that he was shipping distilled water, he would
not violate a statute criminalizing undocumented shipping of
acids). True strict liability might suggest that the defendant need
not know even that he was dealing with a dangerous item.
Nevertheless, we have referred to public welfare offenses as
"dispensing with" or "eliminating" a mens rea requirement or
"mental element," see, e. g., Morissette,
608
B
The Government argues that § 5861(d) defines precisely the sort
of regulatory offense described in Balint. In this view, all guns,
whether or not they are statutory "firearms," are dangerous devices
that put gun owners on notice that they must determine at their
hazard whether their weapons come within the scope of the Act. On
this understanding, the District Court's instruction in this case
was correct, because a conviction can rest simply on proof that a
defendant knew he possessed a "firearm" in the ordinary sense of
the term.
The Government seeks support for its position from our decision
in United States v. Freed,
401 U. S. 601 (1971),
which involved a prosecution for possession of unregistered
grenades under § 5861(d).4 The defendant knew that the items in his
possession were grenades, and we concluded that § 5861(d) did not
require the Government to prove the defendant also knew that the
grenades were unregistered. Id., at 609. To be sure, in deciding
that mens rea was not required with respect to that element of the
offense, we sug-
342 U. S., at 250, 263; United States v. Dotterweich,
320 U. S. 277, 281
(1943), and have described them as strict liability crimes, United
States v. United States Gypsum Co.,
438 U. S. 422, 437
(1978). While use of the term "strict liability" is really a
misnomer, we have interpreted statutes defining public welfare
offenses to eliminate the requirement of mens rea; that is, the
requirement of a "guilty mind" with respect to an element of a
crime. Under such statutes we have not required that the defendant
know the facts that make his conduct fit the definition of the
offense. Generally speaking, such knowledge is necessary to
establish mens rea, as is reflected in the maxim ignorantia facti
excusat. See generally J. Hawley & M. McGregor, Criminal Law
26-30 (1899); R. Perkins, Criminal Law 785-786 (2d ed. 1969); G.
Williams, Criminal Law: The General Part 113174 (1953). Cf. Queen
v. Tolson, 23 Q. B. 168, 187 (1889) (Stephen, J.) ("[I]t may, I
think, be maintained that in every case knowledge of fact [when not
appearing in the statute] is to some extent an element of
criminality as much as competent age and sanity").
4 A grenade is a "firearm" under the Act. 26 U. S. C. §§
5845(a)(8), 5845(f)(1)(B).
609
gested that the Act "is a regulatory measure in the interest of
the public safety, which may well be premised on the theory that
one would hardly be surprised to learn that possession of hand
grenades is not an innocent act." Ibid. Grenades, we explained,
"are highly dangerous offensive weapons, no less dangerous than the
narcotics involved in United States v. Balint." Ibid. But that
reasoning provides little support for dispensing with mens rea in
this case.
As the Government concedes, Freed did not address the issue
presented here. In Freed, we decided only that § 5861(d) does not
require proof of knowledge that a firearm is unregistered. The
question presented by a defendant who possesses a weapon that is a
"firearm" for purposes of the Act, but who knows only that he has a
"firearm" in the general sense of the term, was not raised or
considered. And our determination that a defendant need not know
that his weapon is unregistered suggests no conclusion concerning
whether § 5861(d) requires the defendant to know of the features
that make his weapon a statutory "firearm"; different elements of
the same offense can require different mental states. See Liparota,
471 U. S., at 423, n. 5; United States v. Bailey,
444 U. S. 394, 405-406
(1980). See also W. LaFave & A. Scott, Handbook on Criminal Law
194-195 (1972). Moreover, our analysis in Freed likening the Act to
the public welfare statute in Balint rested entirely on the
assumption that the defendant knew that he was dealing with hand
grenades-that is, that he knew he possessed a particularly
dangerous type of weapon (one within the statutory definition of a
"firearm"), possession of which was not entirely "innocent" in and
of itself. 401 U. S., at 609. The predicate for that analysis is
eliminated when, as in this case, the very question to be decided
is whether the defendant must know of the particular
characteristics that make his weapon a statutory firearm.
Notwithstanding these distinctions, the Government urges that
Freed's logic applies because guns, no less than gre-
610
nades, are highly dangerous devices that should alert their
owners to the probability of regulation. But the gap between Freed
and this case is too wide to bridge. In glossing over the
distinction between grenades and guns, the Government ignores the
particular care we have taken to avoid construing a statute to
dispense with mens rea where doing so would "criminalize a broad
range of apparently innocent conduct." Liparota, 471 U. S., at 426.
In Liparota, we considered a statute that made unlawful the
unauthorized acquisition or possession of food stamps. We
determined that the statute required proof that the defendant knew
his possession of food stamps was unauthorized, largely because
dispensing with such a mens rea requirement would have resulted in
reading the statute to outlaw a number of apparently innocent acts.
Ibid. Our conclusion that the statute should not be treated as
defining a public welfare offense rested on the commonsense
distinction that a "food stamp can hardly be compared to a hand
grenade." Id., at 433.
Neither, in our view, can all guns be compared to hand grenades.
Although the contrast is certainly not as stark as that presented
in Liparota, the fact remains that there is a long tradition of
widespread lawful gun ownership by private individuals in this
country. Such a tradition did not apply to the possession of hand
grenades in Freed or to the selling of dangerous drugs that we
considered in Balint. See also International Minerals, 402 U. S.,
at 563-565; Balint, 258 U. S., at 254. In fact, in Freed we
construed § 5861(d) under the assumption that "one would hardly be
surprised to learn that possession of hand grenades is not an
innocent act." Freed, supra, at 609. Here, the Government
essentially suggests that we should interpret the section under the
altogether different assumption that "one would hardly be surprised
to learn that owning a gun is not an innocent act." That
proposition is simply not supported by common experience. Guns in
general are not "deleterious devices or products or obnoxious waste
materials," International Minerals,
611
supra, at 565, that put their owners on notice that they stand
"in responsible relation to a public danger," Dotterweich, 320 U.
S., at 281.
The Government protests that guns, unlike food stamps, but like
grenades and narcotics, are potentially harmful devices.5 Under
this view, it seems that Liparota's concern for criminalizing
ostensibly innocuous conduct is inapplicable whenever an item is
sufficiently dangerous-that is, dangerousness alone should alert an
individual to probable regulation and justify treating a statute
that regulates the dangerous device as dispensing with mens rea.
But that an item is "dangerous," in some general sense, does not
necessarily suggest, as the Government seems to assume, that it is
not also entirely innocent. Even dangerous items can, in some
cases, be so commonplace and generally available that we would not
consider them to alert individuals to the likelihood of strict
regulation. As suggested above, despite their potential for harm,
guns generally can be owned in perfect innocence. Of course, we
might surely classify certain categories of guns-no doubt including
the machineguns, sawed-off shotguns, and artillery pieces that
Congress has subjected to
5 The dissent's assertions to the contrary notwithstanding, the
Government's position, "[aJccurately identified," post, at 632, is
precisely that "guns in general" are dangerous items. The
Government, like the dissent, cites Sipes v. United States,
321 F.2d
174, 179 (CA8), cert. denied, 375 U. S. 913 (1963), for the
proposition that a defendant's knowledge that the item he possessed
"was a gun" is sufficient for a conviction under § 5861(d). Brief
for United States 21. Indeed, the Government argues that "guns"
should be placed in the same category as the misbranded drugs in
Dotterweich and the narcotics in Balint because '''one would hardly
be surprised to learn' (Freed, 401 U. S. at 609) that there are
laws that affect one's rights of gun ownership." Brief for United
States 22. The dissent relies upon the Government's repeated
contention that the statute requires knowledge that "the item at
issue was highly dangerous and of a type likely to be subject to
regulation." Id., at 9. But that assertion merely patterns the
general language we have used to describe the mens rea requirement
in public welfare offenses and amounts to no more than an assertion
that the statute should be treated as defining a public welfare
offense.
612
regulation-as items the ownership of which would have the same
quasi-suspect character we attributed to owning hand grenades in
Freed. But precisely because guns falling outside those categories
traditionally have been widely accepted as lawful possessions,
their destructive potential, while perhaps even greater than that
of some items we would classify along with narcotics and hand
grenades, cannot be said to put gun owners sufficiently on notice
of the likelihood of regulation to justify interpreting § 5861(d)
as not requiring proof of knowledge of a weapon's
characteristics.6
6 The dissent asserts that the question is not whether all guns
are deleterious devices, but whether a gun "such as the one
possessed by petitioner," post, at 632 (which the dissent
characterizes as a "semiautomatic weapon that [is] readily
convertible into a machinegun," post, at 624, 633, 640), is such a
device. If the dissent intends to suggest that the category of
readily convertible semiautomatics provides the benchmark for
defining the knowledge requirement for § 5861(d), it is difficult
to see how it derives that class of weapons as a standard. As
explained above, see n. 5, supra, the Government's argument has
nothing to do with this ad hoc category of weapons. And the statute
certainly does not suggest that any significance should attach to
readily convertible semiautomatics, for that class bears no
relation to the definitions in the Act. Indeed, in the absence of
any definition, it is not at all clear what the contours of this
category would be. The parties assume that virtually
all
semiautomatics may be converted into automatics, and limiting the
class to those "readily" convertible provides no real guidance
concerning the required mens rea. In short, every owner of a
semiautomatic rifle or handgun would potentially meet such a mens
rea test.
But the dissent apparently does not conceive of the mens rea
requirement in terms of specific categories of weapons at all, and
rather views it as a more fluid concept that does not require
delineation of any concrete elements of knowledge that will apply
consistently from case to case. The dissent sees no need to define
a class of items the knowing possession of which satisfies the mens
rea element of the offense, for in the dissent's view the exact
content of the knowledge requirement can be left to the jury in
each case. As long as the jury concludes that the item in a given
case is "sufficiently dangerous to alert [the defendant] to the
likelihood of regulation," post, at 637, the knowledge requirement
is satisfied. See also post, at 624, 639, 640. But the mens rea
requirement under a criminal statute is a question of law, to be
determined by the court. Our decisions
613
On a slightly different tack, the Government suggests that guns
are subject to an array of regulations at the federal, state, and
local levels that put gun owners on notice that they must determine
the characteristics of their weapons and comply with all legal
requirements.7 But regulation in itself is not sufficient to place
gun ownership in the category of the sale of narcotics in Balint.
The food stamps at issue in Liparota were subject to comprehensive
regulations, yet we did not understand the statute there to
dispense with a mens rea requirement. Moreover, despite the overlay
of legal restrictions on gun ownership, we question whether
regulations on guns are sufficiently intrusive that they impinge
upon the common experience that owning a gun is usually licit and
blameless conduct. Roughly 50 percent of
suggesting that public welfare offenses require that the
defendant know that he stands in "responsible relation to a public
danger," Dotterweich, 320 U. S., at 281, in no way suggest that
what constitutes a public danger is a jury question. It is for
courts, through interpretation of the statute, to define the mens
rea required for a conviction. That task cannot be reduced to
setting a general "standard," post, at 637, that leaves it to the
jury to determine, based presumably on the jurors' personal
opinions, whether the items involved in a particular prosecution
are sufficiently dangerous to place a person on notice of
regulation.
Moreover, as our discussion above should make clear, to
determine as a threshold matter whether a particular statute
defines a public welfare offense, a court must have in view some
category of dangerous and deleterious devices that will be assumed
to alert an individual that he stands in "responsible relation to a
public danger." Dotterweich, supra, at 281. The truncated mens rea
requirement we have described applies precisely because the court
has determined that the statute regulates in a field where knowing
possession of some general class of items should alert individuals
to probable regulation. Under the dissent's approach, however, it
seems that every regulatory statute potentially could be treated as
a public welfare offense as long as the jury-not the
court-ultimately determines that the specific items involved in a
prosecution were sufficiently dangerous.
7 See, e.
g., 18 U. S. C. §§ 921-928 (1988 ed. and Supp.
IV) (requiring licensing of manufacturers, importers, and dealers
of guns and regulating the sale, possession, and interstate
transportation of certain guns).
614
American homes contain at least one firearm of some sort,S and
in the vast majority of States, buying a shotgun or rifle is a
simple transaction that would not alert a person to regulation any
more than would buying a car. 9
If we were to accept as a general rule the Government's
suggestion that dangerous and regulated items place their owners
under an obligation to inquire at their peril into compliance with
regulations, we would undoubtedly reach some untoward results.
Automobiles, for example, might also be termed "dangerous" devices
and are highly regulated at both the state and federal levels.
Congress might see fit to criminalize the violation of certain
regulations concerning automobiles, and thus might make it a crime
to operate a vehicle without a properly functioning emission
control system. But we probably would hesitate to conclude on the
basis of silence that Congress intended a prison term to apply to a
car owner whose vehicle's emissions levels, wholly unbeknownst to
him, began to exceed legal limits between regular inspection
dates.
Here, there can be little doubt that, as in Liparota, the
Government's construction of the statute potentially would impose
criminal sanctions on a class of persons whose mental
state-ignorance of the characteristics of weapons in their
8 See U. S. Dept. of Justice, Bureau of Justice Statistics,
Sourcebook of Criminal Justice Statistics 209 (1992) (Table
2.58).
9 For example, as of 1990, 39 States allowed adult residents,
who are not felons or mentally infirm, to purchase a rifle or
shotgun simply with proof of identification (and in some cases a
simultaneous application for a permit). See U. S. Dept. of Justice,
Bureau of Justice Statistics, Identifying Persons, Other Than
Felons, Ineligible to Purchase Firearms 114, Exh.
BA (1990);
U. S. Congress, Office of Technology Assessment, Automated Record
Checks of Firearm Purchasers 27 (July 1991). See also M. Cooper,
Reassessing the Nation's Gun Laws, Editorial Research Reports 158,
160 (Jan.-Mar. 1991) (table) (suggesting the total is 41 States);
Dept. of Treasury, Bureau of Alcohol, Tobacco and Firearms, State
Laws and Published Ordinances-Firearms (19th ed. 1989).
615
possession-makes their actions entirely innocent.1o The
Government does not dispute the contention that virtually any
semiautomatic weapon may be converted, either by internal
modification or, in some cases, simply by wear and tear, into a
machinegun within the meaning of the Act. Cf. United States v.
Anderson,
885 F.2d
1248, 1251, 12531254 (CA5 1989) (en bane). Such a gun may give
no externally visible indication that it is fully automatic. See
United States v. Herbert,
698 F.2d
981, 986 (CA9), cert. denied, 464 U. S. 821 (1983). But in the
Government's view, any person who has purchased what he believes to
be a semiautomatic rifle or handgun, or who simply has inherited a
gun from a relative and left it untouched in an attic or basement,
can be subject to imprisonment, despite absolute ignorance of the
gun's firing capabilities, if the gun turns out to be an
automatic.
We concur in the Fifth Circuit's conclusion on this point:
"It is unthinkable to us that Congress intended to subject such
law-abiding, well-intentioned citizens to a possible tenyear term
of imprisonment if ... what they genuinely and reasonably believed
was a conventional semi-automatic [weapon] turns out to have worn
down into or been secretly modified to be a fully automatic
weapon." Anderson, supra, at 1254. As we noted in Morissette, the
"purpose and obvious effect of doing away with the requirement of a
guilty intent is to ease the prosecution's path to conviction." 342
U. S., at 263.11 We are reluctant to impute that purpose to
lOWe, of course, express no view concerning the inferences a
jury may have drawn regarding petitioner's knowledge from the
evidence in this case.
11 The Government contends that Congress intended precisely such
an aid to obtaining convictions, because requiring proof of
knowledge would place too heavy a burden on the Government and
obstruct the proper functioning of § 5861 (d). Cf. United States v.
Balint,
258 U. S.
250, 254 (1922) (difficulty of proving knowledge suggests
Congress did not intend to require mens rea). But knowledge can be
inferred from circumstantial
616
Congress where, as here, it would mean easing the path to
convicting persons whose conduct would not even alert them to the
probability of strict regulation in the form of a statute such as §
5861(d).
C
The potentially harsh penalty attached to violation of §
5861(d)-up to 10 years' imprisonment-confirms our reading of the
Act. Historically, the penalty imposed under a statute has been a
significant consideration in determining whether the statute should
be construed as dispensing with mens rea. Certainly, the cases that
first defined the concept of the public welfare offense almost
uniformly involved statutes that provided for only light penalties
such as fines or short jail sentences, not imprisonment in the
state penitentiary. See, e. g., Commonwealth v. Raymond, 97 Mass.
567 (1867) (fine of up to $200 or six months in jail, or both);
Commonwealth v. Farren, 91 Mass. 489 (1864) (fine); People v. Snow
burger, 113 Mich. 86, 71 N. W. 497 (1897) (fine of up to $500 or
incarceration in county jail).12
As commentators have pointed out, the small penalties attached
to such offenses logically complemented the absence of a mens rea
requirement: In a system that generally re-
evidence, including any external indications signaling the
nature of the weapon. And firing a fully automatic weapon would
make the regulated characteristics of the weapon immediately
apparent to its owner. In short, we are confident that when the
defendant knows of the characteristics of his weapon that bring it
within the scope of the Act, the Government will not face great
difficulty in proving that knowledge. Of course, if Congress thinks
it necessary to reduce the Government's burden at trial to ensure
proper enforcement of the Act, it remains free to amend § 5861 (d)
by explicitly eliminating a mens rea requirement.
12 Leading English cases developing a parallel theory of
regulatory offenses similarly involved violations punishable only
by fine or short-term incarceration. See, e. g., Queen v. Woodrow,
15 M. & W. 404, 153 Eng. Rep. 907 (Ex. 1846) (fine of £200 for
adulterated tobacco); Hobbs v. Winchester Corp., [1910] 2 K. B. 471
(maximum penalty of three months' imprisonment for sale of
unwholesome meat).
617
quires a "vicious will" to establish a crime, 4 W. Blackstone,
Commentaries *21, imposing severe punishments for offenses that
require no mens rea would seem incongruous. See Sayre, Public
Welfare Offenses, 33 Colum. L. Rev. 55, 70 (1933). Indeed, some
courts justified the absence of mens rea in part on the basis that
the offenses did not bear the same punishments as "infamous
crimes," Tenement House Dept. v. McDevitt, 215 N. Y. 160, 168, 109
N. E. 88, 90 (1915) (Cardozo, J.), and questioned whether
imprisonment was compatible with the reduced culpability required
for such regulatory offenses. See, e. g., People ex rel. Price v.
Sheffield Farms-Slawson-Decker Co., 225 N. Y. 25, 32-33, 121 N. E.
474, 477 (1918) (Cardozo, J.);
id., at 35, 121 N. E., at 478
(Crane, J., concurring) (arguing that imprisonment for a crime that
requires no mens rea would stretch the law regarding acts mala
prohibita beyond its limitations)P Similarly, commentators
collecting the early cases have argued that offenses punishable by
imprisonment cannot be understood to be public welfare offenses,
but must require mens rea. See R. Perkins, Criminal Law 793-798 (2d
ed. 1969) (suggesting that the penalty should be the starting point
in determining whether a statute describes a public welfare
offense); Sayre, supra, at 72 ("Crimes punishable with prison
sentences ... ordinarily require proof of a guilty intent").14
In rehearsing the characteristics of the public welfare offense,
we, too, have included in our consideration the punishments imposed
and have noted that "penalties commonly are relatively small, and
conviction does no grave damage to an
13 Cf. Queen v. Tolson, 23 Q. B., at 177 (Wills, J.) (In
determining whether a criminal statute dispenses with mens rea,
"the nature and extent of the penalty attached to the offence may
reasonably be considered. There is nothing that need shock any mind
in the payment of a small pecuniary penalty by a person who has
unwittingly done something detrimental to the public
interest").
14 But see, e. g., State v. Lindberg, 125 Wash. 51,215 P. 41
(1923) (applying the public welfare offense rationale to a
felony).
618
offender's reputation." Morissette, 342 U. S., at 256.15 We have
even recognized that it was "[u]nder such considerations" that
courts have construed statutes to dispense with mens rea. Ibid.
Our characterization of the public welfare offense in Morissette
hardly seems apt, however, for a crime that is a felony, as is
violation of § 5861(d).16 After all, "felony" is, as we noted in
distinguishing certain common-law crimes from public welfare
offenses, "'as bad a word as you can give to man or thing.'" Id.,
at 260 (quoting 2 F. Pollock & F. Maitland, History of English
Law 465 (2d ed. 1899)). Close adherence to the early cases
described above might suggest that punishing a violation as a
felony is simply incompatible with the theory of the public welfare
offense. In this view, absent a clear statement from Congress that
mens rea is not required, we should not apply the public welfare
offense rationale to interpret any statute defining a felony
offense as dispensing with mens rea. But see United States v.
Balint,
258 U. S.
250 (1922).
We need not adopt such a definitive rule of construction to
decide this case, however. Instead, we note only that where, as
here, dispensing with mens rea would require the defendant to have
knowledge only of traditionally lawful conduct, a severe penalty is
a further factor tending to suggest that Congress did not intend to
eliminate a mens rea require-
15 See also United States Gypsum, 438 U. S., at 442, n. 18
(noting that an individual violation of the Sherman Antitrust Act
is a felony punishable by three years in prison or a fine not
exceeding $100,000 and stating that "[t]he severity of these
sanctions provides further support for our conclusion that the
[Act] should not be construed as creating strict-liability
crimes"). Cf. Holdridge v. United States,
282
F.2d 302, 310 (CA8 1960) (Blackmun, J.) ("[W]here a federal
criminal statute omits mention of intent and ... where the penalty
is relatively small, where conviction does not gravely besmirch,
[and] where the statutory crime is not one taken over from the
common law, ... the statute can be construed as one not requiring
criminal intent").
16 Title 18 U. S. C. § 3559 makes any crime punishable by more
than one year in prison a felony.
619
ment. In such a case, the usual presumption that a defendant
must know the facts that make his conduct illegal should apply.
III
In short, we conclude that the background rule of the common law
favoring mens rea should govern interpretation of § 5861(d) in this
case. Silence does not suggest that Congress dispensed with mens
rea for the element of § 5861(d) at issue here. Thus, to obtain a
conviction, the Government should have been required to prove that
petitioner knew of the features of his AR-15 that brought it within
the scope of the Act.17
We emphasize that our holding is a narrow one. As in our prior
cases, our reasoning depends upon a commonsense evaluation of the
nature of the particular device or substance Congress has subjected
to regulation and the expectations that individuals may
legitimately have in dealing with the regulated items. In addition,
we think that the penalty attached to § 5861(d) suggests that
Congress did not intend to eliminate a mens rea requirement for
violation of the section. As we noted in Morissette: "Neither this
Court nor,
17 In reaching our conclusion, we find it unnecessary to rely on
the rule of lenity, under which an ambiguous criminal statute is to
be construed in favor of the accused. That maxim of construction
"is reserved for cases where, '[a]fter "seiz[ing] every thing from
which aid can be derived,'" the Court is 'left with an ambiguous
statute.''' Smith v. United States,
508 U. S. 223, 239 (1993)
(quoting United States v. Bass,
404 U. S. 336, 347
(1971), in turn quoting United States v. Fisher, 2 Cranch 358, 386
(1805)). See also United States v. R. L. C.,
503 U. S. 291, 311 (1992)
(THOMAS, J., concurring in part and concurring in judgment);
Chapman v. United States,
500 U. S. 453, 463 (1991)
(rule of lenity inapplicable unless there is a "'grievous ambiguity
or uncertainty'" in the statute). Here, the background rule of the
common law favoring mens rea and the substantial body of precedent
we have developed construing statutes that do not specify a mental
element provide considerable interpretive tools from which we can
"seize aid," and they do not leave us with the ultimate impression
that § 5861 (d) is "grievous[ly]" ambiguous. Certainly, we have not
concluded in the past that statutes silent with respect to mens rea
are ambiguous. See, e. g., United States v. Balint,
258 U. S. 250 (1922).
620
GINSBURG, J., concurring in judgment
so far as we are aware, any other has undertaken to delineate a
precise line or set forth comprehensive criteria for distinguishing
between crimes that require a mental element and crimes that do
not." 342 U. S., at 260. We attempt no definition here, either. We
note only that our holding depends critically on our view that if
Congress had intended to make outlaws of gun owners who were wholly
ignorant of the offending characteristics of their weapons, and to
subject them to lengthy prison terms, it would have spoken more
clearly to that effect. Cf. United States v. Harris,
959 F.2d
246, 261 (CAD C), cert. denied, 506 U. S. 932 (1992).
For the foregoing reasons, the judgment of the Court of Appeals
is reversed, and the case is remanded for further proceedings
consistent with this opinion.
So ordered.
JUSTICE GINSBURG, with whom JUSTICE O'CONNOR joins, concurring
in the judgment.
The statute petitioner Harold E. Staples is charged with
violating, 26 U. S. C. § 5861(d), makes it a crime for any person
to "receive or possess a firearm which is not registered to him."
Although the word "knowingly" does not appear in the statute's
text, courts generally assume that Congress, absent a contrary
indication, means to retain a mens rea requirement. Ante, at 606;
see Liparota v. United States,
471 U. S. 419, 426
(1985); United States v. United States Gypsum
Co., 438 U. S. 422, 437-438
(1978).1 Thus, our holding in United States v. Freed,
401 U. S. 601 (1971),
that § 5861(d) does not require proof of knowledge that the firearm
is unregistered, rested on the premise that the defendant
indeed
1 Contrary to the dissent's suggestion, we have not confined the
presumption of mens rea to statutes codifying traditional
common-law offenses, but have also applied the presumption to
offenses that are "entirely a creature of statute," post, at 625,
such as those at issue in Liparota, Gypsum, and, most recently,
Posters 'N' Things, Ltd. v. United States, ante, at 522-523.
621
knew the items he possessed were hand grenades. Id., at
607;
id., at 612 (Brennan, J., concurring in judgment) ("The
Government and the Court agree that the prosecutor must prove
knowing possession of the items and also knowledge that the items
possessed were hand grenades.").
Conviction under § 5861(d), the Government accordingly concedes,
requires proof that Staples "knowingly" possessed the machine gun.
Brief for United States 23. The question before us is not whether
knowledge of possession is required, but what level of knowledge
suffices: (1) knowledge simply of possession of the object; (2)
knowledge, in addition, that the object is a dangerous weapon; (3)
knowledge, beyond dangerousness, of the characteristics that render
the object subject to regulation, for example, awareness that the
weapon is a machinegun.2
Recognizing that the first reading effectively dispenses with
mens rea, the Government adopts the second, contending that it
avoids criminalizing "apparently innocent conduct," Liparota,
supra, at 426, because under the second reading, "a defendant who
possessed what he thought was a toy or a violin case, but which in
fact was a machinegun, could not be convicted." Brief for United
States 23. The Government, however, does not take adequate account
of the "widespread lawful gun ownership" Congress and the States
have allowed to persist in this country. See United States v.
Harris,
959 F.2d
246, 261 (CAD C) (per curiam), cert. denied, 506 U. S. 932
(1992). Given the notable lack of comprehensive regulation, "mere
unregistered possession of certain types of [regulated
weaponsJ-often [difficult to dis-
2 Some Courts of Appeals have adopted a variant of the third
reading, holding that the Government must show that the defendant
knew the gun was a machine gun, but allowing inference of the
requisite knowledge where a visual inspection of the gun would
reveal that it has been converted into an automatic weapon. See
United States v. O'Mara,
963 F.2d
1288, 1291 (CA9 1992); United States v. Anderson,
885 F.2d
1248, 1251
(CA5 1989) (en bane).
622
GINSBURG, J., concurring in judgment
tinguish] from other, [nonregulated] types," has been held
inadequate to establish the requisite knowledge. See 959
The Nation's legislators chose to place under a registration
requirement only a very limited class of firearms, those they
considered especially dangerous. The generally "dangerous"
character of all guns, the Court therefore observes, ante, at
611-612, did not suffice to give individuals in Staples' situation
cause to inquire about the need for registration. Cf. United States
v. Balint,
258 U. S.
250 (1922) (requiring reporting of sale of strictly regulated
narcotics, opium and cocaine). Only the third reading, then, suits
the purpose of the mens rea requirement-to shield people against
punishment for apparently innocent activity.3
The indictment in Staples' case charges that he "knowingly
received and possessed firearms." 1 App. to Brief for Appellant in
No. 91-5033 (CAlO), p. 1.4 "Firearms" has a
3 The mens rea presumption requires knowledge only of the facts
that make the defendant's conduct illegal, lest it conflict with
the related presumption, "deeply rooted in the American legal
system," that, ordinarily, "ignorance of the law or a mistake of
law is no defense to criminal prosecution." Cheek v. United States,
498 U. S. 192,
199 (1991). Cf. United States v. Freed,
401 U. S. 601, 612 (1971)
(Brennan, J., concurring in judgment) ("If the ancient maxim that
'ignorance of the law is no excuse' has any residual validity, it
indicates that the ordinary intent requirementmens rea-of the
criminal law does not require knowledge that an act is illegal,
wrong, or blameworthy."). The maxim explains why some "innocent"
actors-for example, a defendant who knows he possesses a weapon
with all of the characteristics that subject it to registration,
but was unaware of the registration requirement, or thought the gun
was registered-may be convicted under § 5861(d), see post, at 638.
Knowledge of whether the gun was registered is so closely related
to knowledge of the registration requirement that requiring the
Government to prove the former would in effect require it to prove
knowledge of the law. Cf. Freed, supra, at 612-614 (Brennan, J.,
concurring in judgment).
4 The indictment charged Staples with possession of two
unregistered machineguns, but the jury found him guilty of
knowingly possessing only one of them. Tr.477.
623
circumscribed statutory definition. See 26 U. S. C. § 5845(a).
The "firear[m]" the Government contends Staples possessed in
violation of § 5861(d) is a machine gun. See § 5845(a)(6). The
indictment thus effectively charged that Staples knowingly
possessed a machinegun. "Knowingly possessed" logically means
"possessed and knew that he possessed." The Government can
reconcile the jury instruction 5 with the indictment only on the
implausible assumption that the term "firear[m]" has two different
meanings when used once in the same charge-simply "gun" when
referring to what petitioner knew, and "machine gun" when referring
to what he possessed. See Cunningham, Levi, Green, & Kaplan,
Plain Meaning and Hard Cases, 103 Yale L. J. 1561, 1576-1577
(1994); cf. Ratzlaf v. United States,
510 U. S. 135, 143 (1994)
(construing statutory term to bear same meaning "each time it is
called into play").
For these reasons, I conclude that conviction under § 5861(d)
requires proof that the defendant knew he possessed not simply a
gun, but a machinegun. The indictment in this case, but not the
jury instruction, properly described this knowledge requirement. I
therefore concur in the Court's judgment.
5 The trial court instructed the jury:
"[A] person is knowingly in possession of a thing if his
possession occurred voluntarily and intentionally and not because
of mistake or accident or other innocent reason. The purpose of
adding the word 'knowingly' is to insure that no one can be
convicted of possession of a firearm he did not intend to possess.
The Government need not prove the defendant knows he's dealing with
a weapon possessing every last characteristic [which subjects it]
to the regulation. It would be enough to prove he knows that he is
dealing with a dangerous device of a type as would alert one to the
likelihood of regulation. If he has such knowledge and if the
particular item is, in fact, regulated, then that person acts at
his peril. Mere possession of an unregistered firearm is a
violation of the law of the United States, and it is not necessary
for the Government to prove that the defendant knew that the weapon
in his possession was a firearm within the meaning of the statute,
only that he knowingly possessed the firearm." Id., at 465.
624
JUSTICE STEVENS, with whom JUSTICE BLACKMUN joins,
dissenting.
To avoid a slight possibility of injustice to unsophisticated
owners of machine guns and sawed-off shotguns, the Court has
substituted its views of sound policy for the judgment Congress
made when it enacted the National Firearms Act (or Act). Because
the Court's addition to the text of 26 U. S. C. § 5861(d) is
foreclosed by both the statute and our precedent, I respectfully
dissent.
The Court is preoccupied with guns that "generally can be owned
in perfect innocence." Ante, at 611. This case, however, involves a
semiautomatic weapon that was readily convertible into a
machinegun-a weapon that the jury found to be "'a dangerous device
of a type as would alert one to the likelihood of regulation.'"
Ante, at 604. These are not guns "of some sort" that can be found
in almost "50 percent of American homes." Ante, at 613-614.1 They
are particularly dangerous-indeed, a substantial percentage of the
unregistered machine guns now in circulation are converted
semiautomatic weapons.2
The question presented is whether the National Firearms Act
imposed on the Government the burden of proving beyond a reasonable
doubt not only that the defendant knew he possessed a dangerous
device sufficient to alert him to
1 Indeed, only about 15 percent of all the guns in the United
States are semiautomatic. See National Rifle Association, Fact
Sheet, SemiAutomatic Firearms 1 (Feb. 1, 1994). Although it is not
known how many of those weapons are readily convertible into
machineguns, it is obviously a lesser share of the total.
2 See U. S. Dept. of Justice, Attorney General's Task Force on
Violent Crime: Final Report 29, 32 (Aug. 17, 1981) (stating that
over an 18-month period over 20 percent of the machineguns seized
or purchased by the Bureau of Alcohol, Tobacco and Firearms had
been converted from semiautomatic weapons by "simple tool work or
the addition of readily available parts") (citing U. S. Dept. of
Treasury, Bureau of Alcohol, Tobacco and Firearms, Firearms Case
Summary (Washington: U. S. Govt. Printing Office 1981)).
625
regulation, but also that he knew it had all the characteristics
of a "firearm" as defined in the statute. Three unambiguous
guideposts direct us to the correct answer to that question: the
text and structure of the Act, our cases construing both this Act
and similar regulatory legislation, and the Act's history and
interpretation.
I
Contrary to the assertion by the Court, the text of the statute
does provide "explicit guidance in this case." Cf. ante, at 605.
The relevant section of the Act makes it "unlawful for any person
... to receive or possess a firearm which is not registered to him
in the National Firearms Registration and Transfer Record." 26 U.
S. C. § 5861(d). Significantly, the section contains no knowledge
requirement, nor does it describe a common-law crime.
The common law generally did not condemn acts as criminal unless
the actor had "an evil purpose or mental culpability," Morissette
v. United States,
342
U. S. 246, 252 (1952), and was aware of all the facts that made
the conduct unlawful, United States v. Balint,
258 U. S. 250, 251-252
(1922). In interpreting statutes that codified traditional
common-law offenses, courts usually followed this rule, even when
the text of the statute contained no such requirement. Ibid.
Because the offense involved in this case is entirely a creature of
statute, however, "the background rules of the common law," cf.
ante, at 605, do not require a particular construction, and
critically different rules of construction apply. See Morissette v.
United States, 342 U. S., at 252-260.
In Morissette, Justice Jackson outlined one such interpre-
tive rule:
"Congressional silence as to mental elements in an Act merely
adopting into federal statutory law a concept of crime already ...
well defined in common law and statutory interpretation by the
states may warrant quite contrary inferences than the same silence
in creating an of-
626
fense new to general law, for whose definition the courts have
no guidance except the Act." Id., at 262.
Although the lack of an express knowledge requirement in §
5861(d) is not dispositive, see United States v. United States
Gypsum Co., 438 U. S. 422, 438
(1978), its absence suggests that Congress did not intend to
require proof that the defendant knew all of the facts that made
his conduct illega1.3
The provision's place in the overall statutory scheme, see
Crandon v. United States,
494 U. S. 152, 158
(1990), confirms this intention. In 1934, when Congress originally
enacted the statute, it limited the coverage of the 1934 Act to a
relatively narrow category of weapons such as submachineguns and
sawed-off shotguns-weapons characteristically used only by
professional gangsters like Al Capone, Pretty Boy Floyd, and their
henchmen.4 At the time, the Act would have had little application
to guns used by hunters or guns kept at home as protection against
unwelcome intruders.5
3 The Seventh Circuit's comment in a similar case is equally apt
here:
"The crime is possessing an unregistered firearm-not 'knowingly'
possessing an unregistered firearm, or possessing a weapon knowing
it to be a firearm, or possessing a firearm knowing it to be
unregistered .... [Petitioner's] proposal is not that we interpret
a knowledge or intent requirement in § 5861(d); it is that we
invent one." United States v. Ross,
917 F.2d
997, 1000 (1990) (per curiam) (emphasis in original), cert.
denied, 498 U. S. 1122 (1991).
4 "The late 1920s and early 1930s brought ... a growing
perception of crime both as a major problem and as a national one
.... [C]riminal gangs found the submachinegun (a fully automatic,
shoulder-fired weapon utilizing automatic pistol cartridges) and
sawed-off shotgun deadly for close-range fighting." Hardy, The
Firearms Owners' Protection Act: A Historical and Legal
Perspective, 17 Cumb. L. Rev. 585, 590 (1987).
5 The Senate Report on the bill explained: "The gangster as a
law violator must be deprived of his most dangerous weapon, the
machine gun. Your committee is of the opinion that limiting the
bill to the taxing of sawed-off guns and machineguns is sufficient
at this time. It is not thought necessary to go so far as to
include pistols and revolvers and sporting arms. But while there is
justification for permitting the citizen to keep a pistol or
revolver for his own protection without any restriction,
627
Congress therefore could reasonably presume that a person found
in possession of an unregistered machinegun or sawed-off shotgun
intended to use it for criminal purposes. The statute as a whole,
and particularly the decision to criminalize mere possession,
reflected a legislative judgment that the likelihood of innocent
possession of such an unregistered weapon was remote, and far less
significant than the interest in depriving gangsters of their
use.
In addition, at the time of enactment, this Court had already
construed comparable provisions of the Harrison Anti-Narcotic Act
not to require proof of knowledge of all the facts that constitute
the proscribed offense. United States v. Balint,
258 U. S. 250 (1922).6
Indeed, Attorney General Cummings expressly advised Congress that
the text of the gun control legislation deliberately followed the
language of the Anti-Narcotic Act to reap the benefit of cases
construing it.7 Given the reasoning of Balint, we properly may
infer that Congress did not intend the Court to read a stricter
knowledge requirement into the gun controllegislation than we read
into the Anti-Narcotic Act. Cannon v. University of Chicago,
441 U. S. 677,
698-699 (1979).
Like the 1934 Act, the current National Firearms Act is
primarily a regulatory measure. The statute establishes
there is no reason why anyone except a law officer should have a
machinegun or sawed-off shotgun." S. Rep. No. 1444, 73d Cong., 2d
Sess., 1-2 (1934).
6 In the
Balint case, after acknowledging the general
common-law rule that made knowledge of the facts an element of
every crime, we held that as to statutory crimes the question is
one of legislative intent, and that the Anti-Narcotic Act should be
construed to authorize "punishment of a person for an act in
violation of law[,] [even] when ignorant of the facts making it
so."
Balint, 258 U. S., at 251-252. The "policy of the law
may, in order to stimulate proper care, require the punishment of
the negligent person though he be ignorant of the noxious character
of what he sells." Id., at 253.
7 See National Firearms Act: Hearings on H. R. 9066 before the
House Committee on Ways and Means, 73d Cong., 2d Sess., 6
(1934).
628
taxation, registration, reporting, and recordkeeping
requirements for businesses and transactions involving statutorily
defined firearms, and requires that each firearm be identified by a
serial number. 26 U. S. C. §§ 5801-5802, 5811-5812,
5821-5822,5842-5843. The Secretary of the Treasury must maintain a
central registry that includes the names and addresses of persons
in possession of all firearms not controlled by the Government. §
5841. Congress also prohibited certain acts and omissions,
including the possession of an unregistered firearm.8 § 5861.
As the Court acknowledges, ante, at 607, to interpret statutory
offenses such as § 5861(d), we look to "the nature of the statute
and the particular character of the items regulated" to determine
the level of knowledge required for conviction. An examination of §
5861(d) in light of our precedent dictates that the crime of
possession of an unregistered machine gun is in a category of
offenses described as "public welfare" crimes.9 Our decisions
interpreting such offenses clearly require affirmance of
petitioner's conviction.
II
"Public welfare" offenses share certain characteristics: (1)
they regulate "dangerous or deleterious devices or products
8 "Omission of a mental element is the norm for statutes
designed to deal with inaction. Not registering your gun, not
cleaning up your warehouse, United States v. Park,
421 U. S. 658 ... (1975),
and like 'acts' are done without thinking. Often the omission
occurs because of lack of attention .... Yet Congress may have
sound reasons for requiring people to investigate and act,
objectives that cannot be achieved if the courts add mental
elements to the statutes." Ross, 917 F. 2d, at 1000.
9 These statutes are sometimes referred to as "strict liability"
offenses.
As the Court notes, because the defendant must know that he is
engaged in the type of dangerous conduct that is likely to be
regulated, the use of the term "strict liability" to describe these
offenses is inaccurate. Ante, at 607-608, n. 3. I therefore use the
term "public welfare offense" to describe this type of statute.
629
or obnoxious waste materials," see United States v.
International Minerals & Chemical Corp.,
402 U. S. 558, 565
(1971); (2) they "heighten the duties of those in control of
particular industries, trades, properties or activities that affect
public health, safety or welfare," Morissette, 342 U. S., at 254;
and (3) they "depend on no mental element but consist only of
forbidden acts or omissions,"
id., at 252-253. Examples of
such offenses include Congress' exertion of its power to keep
dangerous narcotics,lO hazardous substances,l1 and impure and
adulterated foods and drugs 12 out of the channels of commerce.
13
Public welfare statutes render criminal "a type of conduct that
a reasonable person should know is subject to stringent public
regulation and may seriously threaten the community's health or
safety." Liparota v. United States,
471 U. S. 419, 433
(1985). Thus, under such statutes, "a defendant can be convicted
even though he was unaware of the circumstances of his conduct that
made it illegal." Id., at 443, n. 7 (White, J., dissenting).
Referring to the strict criminal sanctions for unintended
violations of the food and drug laws, Justice Frankfurter
wrote:
"The purposes of this legislation thus touch phases of the lives
and health of people which, in the circumstances of modern
industrialism, are largely beyond self-protection. Regard for these
purposes should in-
10 See United States v. Balint,
258 U. S. 250 (1922).
11 See United States v. International Minerals & Chemical
Corp., 402
12 See United States v. Dotterweich,
320 U. S. 277 (1943).
13 The Court in Morissette v. United States,
342 U. S. 246 (1952),
expressing approval of our public welfare offense cases,
stated:
"Neither this Court nor, so far as we are aware, any other has
undertaken to delineate a precise line or set forth comprehensive
criteria for distinguishing between crimes that require a mental
element and crimes that do not. We attempt no closed definition,
for the law on the subject is neither settled nor static." Id., at
260 (footnotes omitted).
630
fuse construction of the legislation if it is to be treated as a
working instrument of government and not merely as a collection of
English words. The prosecution ... is based on a now familiar type
of legislation whereby penalties serve as effective means of
regulation. Such legislation dispenses with the conventional
requirement for criminal conduct-awareness of some wrongdoing. In
the interest of the larger good it puts the burden of acting at
hazard upon a person otherwise innocent but standing in responsible
relation to a public danger." United States v. Dotterweich,
320 U. S. 277,
280-281 (1943) (citing United States v. Balint, 258 U. S. 250 (1922);
other citations omitted).
The National Firearms Act unquestionably is a public welfare
statute. United States v. Freed,
401 U. S. 601, 609 (1971)
(holding that this statute "is a regulatory measure in the interest
of the public safety"). Congress fashioned a legislative scheme to
regulate the commerce and possession of certain types of dangerous
devices, including specific kinds of weapons, to protect the health
and welfare of the citizenry. To enforce this scheme, Congress
created criminal penalties for certain acts and omissions. The text
of some of these offenses-including the one at issue herecontains
no knowledge requirement.
The Court recognizes:
"[WJe have reasoned that as long as a defendant knows that he is
dealing with a dangerous device of a character that places him 'in
responsible relation to a public danger,' Dotterweich, supra, at
281, he should be alerted to the probability of strict regulation,
and we have assumed that in such cases Congress intended to place
the burden on the defendant to 'ascertain at his peril whether [his
conduct] comes within the inhibition of the statute.' Balint, 258
U. S., at 254." Ante, at 607.
631
We thus have read a knowledge requirement into public welfare
crimes, but not a requirement that the defendant know all the facts
that make his conduct illegal. Although the Court acknowledges this
standard, it nevertheless concludes that a gun is not the type of
dangerous device that would alert one to the possibility of
regulation.
Both the Court and JUSTICE GINSBURG erroneously rely upon the
"tradition[al]" innocence of gun ownership to find that Congress
must have intended the Government to prove knowledge of all the
characteristics that make a weapon a statutory "firear[m]." Ante,
at 610-612; ante, at 621-622 (GINSBURG, J., concurring in
judgment). We held in Freed, however, that a § 5861(d) offense may
be committed by one with no awareness of either wrongdoing or of
all the facts that constitute the offense.14 401 U. S., at 607-610.
Nevertheless, the Court, asserting that the Government "gloss[es]
over the distinction between grenades and guns," determines that
"the gap between Freed and this case is too wide to bridge." Ante,
at 610. As such, the Court instead reaches the rather surprising
conclusion that guns are more analogous to food stamps than to hand
grenades.15 Even if
14 Freed, 401 U. S., at 607 (holding that a violation of § 5861
(d) may be established without proof that the defendant was aware
of the fact that the firearm he possessed was unregistered). Our
holding in Freed is thus squarely at odds with the Court's
conclusion that the "defendant must know the facts that make his
conduct illegal," ante, at 619.
15The Court's and JUSTICE GINSBURG'S reliance upon Liparota
v.
United States,
471
U. S. 419 (1985), is misplaced. Ante, at 610-612; ante, at
621-622. Although the Court is usually concerned with fine nuances
of statutory text, its discussion of Liparota simply ignores the
fact that the food stamp fraud provision, unlike § 5861(d),
contained the word "knowingly." The Members of the Court in
Liparota disagreed on the proper interpretation. The dissenters
accepted the Government's view that the term merely required proof
that the defendant had knowledge of the facts that constituted the
crime. See Liparota, 471 U. S., at 442-443 (White, J., dissenting)
("I would read § 2024(b)(1) ... to require awareness of only the
relevant aspects of one's conduct rendering it illegal, not the
632
one accepts that dubious proposition, the Court founds it upon a
faulty premise: its mischaracterization of the Government's
submission as one contending that "all guns ... are dangerous
devices that put gun owners on notice ... " Ante, at 608 (emphasis
added).16 Accurately identified, the Government's position presents
the question whether guns such as the one possessed by petitioner"
'are highly dangerous offensive weapons, no less dangerous than the
narcotics'" in Balint or the hand grenades in Freed, see ante, at
609 (quoting Freed, 401 U. S., at
609).17
fact of illegality"). The majority, however, concluded that
"knowingly" also connoted knowledge of illegality. Id., at 424-425.
Because neither "knowingly" nor any comparable term appears in §
5861(d), the statute before us today requires even less proof of
knowledge than the dissenters would have demanded in Liparota.
16JUSTICE GINSBURG similarly assumes that the character of "all
guns" cannot be said to place upon defendants an obligation "to
inquire about the need for registration." Ante, at 622 (emphasis
added).
17 The Government does note that some Courts of Appeals have
required proof of knowledge only that "the weapon was 'a firearm,
within the general meaning of that term,'" Brief for United States
24-25 (citing cases). Contrary to the assertion by the Court, ante,
at 632, n. 5, however, the Government does not advance this test as
the appropriate knowledge requirement, but instead supports the one
used by other Courts of Appeals. Compare the Court's description of
the Government's position,
ibid., with the following
statements in the Government's brief:
"A defendant may be convicted of such offenses so long as the
government proves that he knew the item at issue was highly
dangerous and of a type likely to be subject to regulation." Brief
for United States 9.
"[T]he court of appeals correctly required the government to
prove only that petitioner knew that he possessed a dangerous
weapon likely to be subject to regulation." Id., at 13.
"B. The intent requirement applicable to Section 5861(d) is
knowledge that one is dealing with a dangerous item of a type
likely to be subject to regulation." Id., at 16.
"But where a criminal statute involves regulation of a highly
hazardous substance-and especially where it penalizes a failure to
act or to comply with a registration scheme-the defendant's
knowledge that he was deal-
633
Thus, even assuming that the Court is correct that the mere
possession of an ordinary rifle or pistol does not entail
sufficient danger to alert one to the possibility of regulation,
that conclusion does not resolve this case. Petitioner knowingly
possessed a semiautomatic weapon that was readily convertible into
a machine gun. The" 'character and nature' " of such a weapon is
sufficiently hazardous to place the possessor on notice of the
possibility of regulation. See Posters 'N' Things, Ltd. v. United
States, ante, at 525 (citation omitted).18 No significant
difference exists between
ing with such a substance and that it was likely to be subject
to regulation provides sufficient intent to support a conviction."
Id., at 17-18.
"Rather, absent contrary congressional direction, knowledge of
the highly dangerous nature of the articles involved and the
likelihood that they are subject to regulation takes the place of
the more rigorous knowledge requirement applicable where apparently
innocent and harmless devices are subject to regulation." Id., at
20.
"But the instruction did not require the government to prove
that petitioner knew his weapon 'possess[ed] every last
characteristic [which subjects it] to regulation'; he need only
have 'know[n] that he [was] dealing with a dangerous device of a
type as would alert one to the likelihood of regulation.' Tr.
465.
"That instruction accurately describes the mental state
necessary for a violation of Section 5861(d)." Id., at 23.
"[P]roof that a defendant was on fair notice that the item he
possessed was highly dangerous and likely to be regulated is
sufficient to support a conviction." Id., at 24.
18The Court and JUSTICE GINSBURG apparently assume that the
outer limits of any such notice can be no broader than the category
of dangerous objects that Congress delineated as "firearms." Ante,
at 611-612; ante, at 621-622. Our holding in Posters 'N' Things,
illustrates the error in that assumption. A retailer who may not
know whether certain merchandise is actually drug paraphernalia, as
that term is defined in the relevant federal statute, may
nevertheless violate the law if "aware that customers in general
are likely to use the merchandise with drugs." Ante, at 524. The
owner of a semiautomatic weapon that is readily convertible into a
machinegun can certainly be aware of its dangerous nature and the
consequent probability of regulation even if he does not know
whether the
634
imposing upon the possessor a duty to determine whether such a
weapon is registered, Freed, 401 U. S., at 607-610, and imposing a
duty to determine whether that weapon has been converted into a
machinegun.
Cases arise, of course, in which a defendant would not know that
a device was dangerous unless he knew that it was a "firearm" as
defined in the Act. Freed was such a case; unless the defendant
knew that the device in question was a hand grenade, he would not
necessarily have known that it was dangerous. But given the text
and nature of the statute, it would be utterly implausible to
suggest that Congress intended the owner of a sawed-off shotgun to
be criminally liable if he knew its barrel was 17.5 inches long but
not if he mistakenly believed the same gun had an 18inch barrel.
Yet the Court's holding today assumes that Congress intended that
bizarre result.
The enforcement of public welfare offenses always entails some
possibility of injustice. Congress nevertheless has repeatedly
decided that an overriding public interest in health or safety may
outweigh that risk when a person is dealing with products that are
sufficiently dangerous or deleterious to make it reasonable to
presume that he either knows, or should know, whether those
products conform to special regulatory requirements. The dangerous
character of the product is reasonably presumed to provide
sufficient notice of the probability of regulation to justify
strict enforcement against those who are merely guilty of
negligent, rather than willful, misconduct.
The National Firearms Act is within the category of public
welfare statutes enacted by Congress to regulate highly dangerous
items. The Government submits that a conviction under such a
statute may be supported by proof that the
weapon is actually a machine gun. If ignorance of the precise
characteristics that render an item forbidden should be a defense,
items that are likely to be "drug paraphernalia" are no more
obviously dangerous, and thus regulated, than items that are likely
to be "firearms."
635
defendant "knew the item at issue was highly dangerous and of a
type likely to be subject to regulation." Brief for United States
9.19 It is undisputed that the evidence in this case met that
standard. Nevertheless, neither JUSTICE THOMAS for the Court nor
JUSTICE GINSBURG has explained why such a knowledge requirement is
unfaithful to our cases or to the text of the Act.20 Instead,
following the approach of their decision in United States v.
Harris,
959 F.2d
246, 260-261 (CAD C) (per curiam), cert. denied sub nom. Smith
v. United States, 506 U. S. 932 (1992), they have simply explained
why, in their judgment, it would be unfair to punish the possessor
of this machinegun.
III
The history and interpretation of the National Firearms Act
supports the conclusion that Congress did not intend to
19 As a matter of law, this is the level of knowledge required
by the statute. Therefore, contrary to the Court's suggestion,
ante, at 612, n. 6, I have not left the determination of the "exact
content of the knowledge requirement" to the jury. I only leave to
the jury its usual function: the application of this legal standard
to the facts. In performing this function, juries are frequently
required to determine if a law has been violated by application of
just such a "general 'standard.''' See, e.
g., Posters 'N'
Things, ante, at 523-525; Miller v. California,
413 U. S. 15, 24
(1973).
20 The Court also supports its conclusion on the basis of the
purported disparity between the penalty provided by this statute
and those of other regulatory offenses. Although a modest penalty
may indicate that a crime is a public welfare offense, such a
penalty is not a requisite characteristic of public welfare
offenses. For example, the crime involved in Balint involved
punishment of up to five years' imprisonment. See Dotterweich, 320
U. S., at 285; see also Morissette, 342 U. S., at 251, n. 8 (noting
that rape of one too young to consent is an offense "in which the
victim's actual age was determinative despite defendant's
reasonable belief that the girl had reached age of consent").
Moreover, congressional authorization of a range of penalties in
some cases-petitioner, for instance, is on probation-demonstrates a
recognition that relatively innocent conduct should be punished
less severely.
636
require knowledge of all the facts that constitute the offense
of possession of an unregistered weapon. During the first 30 years
of enforcement of the 1934 Act, consistent with the absence of a
knowledge requirement and with the reasoning in Balint, courts
uniformly construed it not to require knowledge of all the
characteristics of the weapon that brought it within the statute.
In a case decided in 1963, then-Judge Blackmun reviewed the earlier
cases and concluded that the defendant's knowledge that he
possessed a gun was "all the scienter which the statute requires."
Sipes v. United States,
321 F.2d
174, 179 (CA8), cert. denied, 375 U. S. 913 (1963).
Congress subsequently amended the statute twice, once in 1968
and again in 1986. Both amendments added knowledge requirements to
other portions of the Act,21 but neither the text nor the history
of either amendment discloses an intent to add any other knowledge
requirement to the possession of an unregistered firearm offense.
Given that, with only one partial exception,22 every federal
tribunal to address the question had concluded that proof of
knowledge of all the facts constituting a violation was not
required for a convic-
21 Significantly, in 1968, Congress included a knowledge
requirement in § 5861(Z). 26 U. S. C. § 5861(Z) (making it unlawful
"to make, or cause the making of, a false entry on any application,
return, or record required by this chapter, knowing such entry to
be false") (emphasis added). "[W]here Congress includes particular
language in one section of a statute but omits it in another
section of the same Act, it is generally presumed that Congress
acts intentionally and purposely in the disparate inclusion or
exclusion." Rodriguez v. United States,
480 U. S. 522, 525 (1987)
(internal quotation marks and citations omitted); see also Lawrence
County v. Lead-Deadwood School Dist. No. 40-1,
469 U. S. 256, 267-268
(1985).
22 United States v. Herbert,
698 F.2d
981, 986-987 (CA9), cert. denied, 464 U. S. 821 (1983)
(requiring the Government to prove knowledge of all the
characteristics of a weapon only when no external signs indicated
that the weapon was a "firearm"). Not until 1989 did a Court of
Appeals adopt the view of the majority today. See United States v.
Williams, 872 F. 2d
773 (CA6).
637
tion under § 5861(d),23 we may infer that Congress intended that
interpretation to survive. See Lorillard v. Pons,
434 U. S. 575, 580
(1978).
In short, petitioner's knowledge that he possessed an item that
was sufficiently dangerous to alert him to the likelihood of
regulation would have supported a conviction during the first half
century of enforcement of this statute. Unless application of that
standard to a particular case violates the Due Process Clause,24 it
is the responsibility of Congress, not this Court, to amend the
statute if Congress deems it unfair or unduly strict.
IV
On the premise that the purpose of the mens rea requirement is
to avoid punishing people "for apparently innocent activity,"
JUSTICE GINSBURG concludes that proof of knowledge that a weapon is
"'a dangerous device of a type as would alert one to the likelihood
of regulation'" is not an adequate mens rea requirement, but that
proof of knowledge that the weapon possesses" 'every last
characteristic'" that subjects it to regulation is. Ante, at
622-623, and n. 5 (GINSBURG, J., concurring in judgment) (quoting
the trial court's jury instruction).
23 See, e. g., United States v. Gonzalez,
719
F.2d 1516, 1522 (CAll 1983), cert. denied, 465 U. S. 1037
(1984); Morgan v. United States,
564 F.2d
803, 805-806 (CA8 1977); United States v. Cowper,
503 F.2d
130, 132-133 (CA6 1974), cert. denied, 420 U. S. 930 (1975);
United States v. DeBartolo,
482 F.2d
312, 316 (CA1 1973); United States v. Vasquez,
476 F.2d
730, 732 (CA5), cert. denied, 414 U. S. 836 (1973), overruled
by United States v. Anderson,
885 F.2d
1248 (CA5 1989) (en bane).
And, as I have already noted, United States v. Freed,
401 U. S. 601 (1971), was
consistent with the Government's position here. Although the
Government accepted the burden of proving that Freed knew that the
item he possessed was a hand grenade, the possessor of an
unfamiliar object such as a hand grenade would not know that it was
"a dangerous item of a type likely to be subject to regulation,"
Brief for United States 16; see also
id., at 20, 23, 24,
unless he knew what it was.
24 Petitioner makes no such claim in this Court.
638
Assuming that "innocent activity" describes conduct without any
consciousness of wrongdoing, the risk of punishing such activity
can be avoided only by reading into the statute the common-law
concept of mens rea: "an evil purpose or mental culpability."
Morissette, 342 U. S., at 252.25 But even petitioner does not
contend that the Government must prove guilty intent or intentional
wrongdoing. Instead, the "mens rea" issue in this case is simply
what knowledge requirement, if any, Congress implicitly included in
this offense. There are at least five such possible knowledge
requirements, four of which entail the risk that a completely
innocent mistake will subject a defendant to punishment.
First, a defendant may know that he possesses a weapon with all
of the characteristics that make it a "firearm" within the meaning
of the statute and also know that it has never been registered, but
be ignorant of the federal registration requirement. In such a
case, we presume knowledge of the law even if we know the defendant
is "innocent" in the sense that JUSTICE GINSBURG uses the word.
Second, a defendant may know that he possesses a weapon with all of
the characteristics of a statutory firearm and also know that the
law requires that it be registered, but mistakenly believe that it
is in fact registered. Freed squarely holds that this defendant's
"innocence" is not a defense. Third, a defendant
25 Our use of the term mens rea has not been consistent. In
Morissette, we used the term as if it always connoted a form of
wrongful intent. In other cases, we employ it simply to mean
whatever level of knowledge is required for any particular crime.
See, e. g., United States v. Bailey,
444 U. S. 394, 403
(1980). In this sense, every crime except a true strictliability
offense contains a mens rea requirement. For instance, the Court
defined mens rea in Liparota v. United States, 471 U. S., at 426,
as "knowledge of illegality." In dissent, however, Justice White
equated the term with knowledge of the facts that make the conduct
illegal. Id., at 442-443. Today, the Court assigns the term the
latter definition, ante, at 605, but in fact requires proof of
knowledge of only some of the facts that constitute the violation,
ante, at 609 (not requiring proof of knowledge of the fact that the
gun is unregistered).
639
may know only that he possesses a weapon with all of the
characteristics of a statutory firearm. Neither ignorance of the
registration requirement nor ignorance of the fact that the weapon
is unregistered protects this "innocent" defendant. Fourth, a
defendant may know that he possesses a weapon that is sufficiently
dangerous to likely be regulated, but not know that it has all the
characteristics of a statutory firearm. Petitioner asserts that he
is an example of this "innocent" defendant. Fifth, a defendant may
know that he possesses an ordinary gun and, being aware of the
widespread lawful gun ownership in the country, reasonably assume
that there is no need "to inquire about the need for registration."
Ante, at 622 (GINSBURG, J., concurring in judgment). That, of
course, is not this case. See supra, at 624, and n. 1.26
JUSTICE GINSBURG treats the first, second, and third
alternatives differently from the fourth and fifth. Her acceptance
of knowledge of the characteristics of a statutory "firearm" as a
sufficient predicate for criminal liability-despite ignorance of
either the duty to register or the fact of nonregistration, or
both-must rest on the premise that such knowledge would alert the
owner to the likelihood of regulation, thereby depriving the
conduct of its "apparen[t] innocen[ce]." Yet in the fourth
alternative, a jury determines just such knowledge: that the
characteristics of the weapon known to the defendant would alert
the owner to the likelihood of regulation.
In short, JUSTICE GINSBURG'S reliance on "the purpose of the
mens rea requirement-to shield people against punishment for
apparently innocent activity," ante, at 622, neither explains why
ignorance of certain facts is a defense although
26 Although I disagree with the assumption that "widespread
lawful gun ownership" provides a sufficient reason for believing
that there is no need to register guns (there is also widespread
lawful automobile ownership), acceptance of that assumption neither
justifies the majority's holding nor contradicts my conclusion on
the facts of this case.
640
ignorance of others is not, nor justifies her disagreement with
the jury's finding that this defendant knew facts that should have
caused him to inquire about the need for registration.27
V
This case presents no dispute about the dangerous character of
machineguns and sawed-off shotguns. Anyone in possession of such a
weapon is "standing in responsible relation to a public danger."
See Dotterweich, 320 U. S., at 281 (citation omitted). In the
National Firearms Act, Congress determined that the serious threat
to health and safety posed by the private ownership of such
firearms warranted the imposition of a duty on the owners of
dangerous weapons to determine whether their possession is lawful.
Semiautomatic weapons that are readily convertible into machineguns
are sufficiently dangerous to alert persons who knowingly possess
them to the probability of stringent public regulation. The jury's
finding that petitioner knowingly possessed "a dangerous device of
a type as would alert one to the likelihood of regulation"
adequately supports the conviction.
Accordingly, I would affirm the judgment of the Court of
Appeals.
27 In addition, contrary to JUSTICE GINSBURG'S assumption, if
one reads the term "firearm" from the quoted section of the
indictment to mean "gun," the indictment still charges an offense
under § 5861 (d) and does not differ from the critical jury
instruction. See ante, at 622-623. Even if JUSTICE GINSBURG is
correct that there is a technical variance, petitioner makes no
claim that any such variance prejudiced him. The wording of the
indictment, of course, sheds no light on the proper interpretation
of the underlying statutory text. Although the repeated use of a
term in a statute may shed light on the statute's construction, see
Ratzlafv. United States,
510 U. S. 135, 143
(1994), such use in an indictment is irrelevant to that
question.
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